Uncontrolled essential hypertension (EH) is a major risk factor for stroke, renal failure and cardiovascular events. Hispanics have the highest rate of uncontrolled EH (BP e 140/90 mmHg) in the U.S. Two primary responsible factors are patient medication non-adherence and clinician failure to intensify therapy in timely manners (i.e., therapeutic inertia). BP control programs are needed which can be sustained by EHs and readily disseminated by healthcare providers. There have been no randomized controlled trials (RCTs) evaluating theory driven culturally tailored mobile health technology applications among Hispanics with uncontrolled EH. In response to PA-12-023, the proposed R21 research proposal will test and refine the Smart phone Medication Adherence Stops Hypertension (SMASH) program. SMASH includes multi-level components: 1) automated reminders from an electronic medication tray; 2) tailored text message/voice mail motivational feedback and reinforcement based upon adherence to daily medication and BP monitoring; 3) automated summary reports and direct alerts to providers and 4) booster program for SMASHers who show deterioration in BP control and/or medication adherence after the 3 month trial. The aims are as follows: Aim 1a: Conduct 3 month 2 arm (SMASH vs. enhanced Standard Care [SC]) feasibility RCT with 6 month follow up in 60 uncontrolled EH 21-55 year old Hispanics. Primary feasibility outcomes are measures of recruitment and retention rates, intervention use and patient and provider satisfaction, and Aim 1b: Obtain estimates of variability of changes in primary outcomes of BP changes (i.e. % reaching JN7 designated BP control: resting BP <140/90 mmHg). Other BP measures include: % reaching 24-hour BP control: < 130/80 mmHg) and absolute reductions in resting and 24-hour BP at 3, 6, and 9 months. Secondary outcomes: patient adherence (med intake, BP self-monitoring), self-determination theory constructs of self-efficacy and intrinsic motivation (i.e., autonomous regulation) and provider adherence to JNC7 guidelines (timing of med changes). Aim 2. Conduct focus groups after 6 month final follow-up with providers and staff (n=6-10) and random sample of SMASHers (n=16) to assess key user reactions including perceived cultural sensitivity, acceptability, usability, salience & sustainability facilitators/barriers. Aim 3. Triangulate data from Aims 1 and 2 to further refine and optimize SMASH and prepare for a full-scale efficacy/effectiveness RCT (PA-12-022, R01). Long-term objective is to develop practical, effective and sustainable mHealth primary and secondary prevention programs for EH and CVD. Dissemination of SMASH across ethnic/racial groups will help ameliorate the burden of CVD and associated health disparities.